How to change signaltap trigger using TCL

Hi,

I am using tcl to capture signaltap data.

The .stp file has a predefined trigger, based on a counter reaching a certain value.

I want to capture data for different counter values.

What I have so far:

open_session -name $signaltap_file
run -hardware_name $usb_blaster -device_name $device -instance auto_signaltap_0 -data_log log_1

I am aware of the -trigger option for the run command, but I have no idea how to use it.

Any ideas?